Composite heat-seal film and method for producing the same

Abstract

The application relates to the technical field of heat-seal film, and particularly discloses a composite heat-seal film and a preparation method thereof.The composite heat-seal film is composed of a base layer and a heat-seal layer; the base layer comprises modified PET, aminated basalt powder, an antistatic agent and the like; and the heat-seal layer comprises PETG, PCL, cellulose acetate, an adhesion promoter, an antioxidant and the like.The preparation method of the composite heat-seal film comprises the following steps: S1, mixing modified PET, aminated basalt powder and an antistatic agent, and then melt-extruding to obtain material A; S2, first treating the mixture of PETG and PCL by using plasma, and then mixing cellulose acetate, an adhesion promoter and an antioxidant, and then melt-extruding to obtain material B; and S3, adopting a co-extrusion process to obtain the composite heat-seal film from the material A and the material B.The preparation steps are simple, the cost is low, the method is suitable for industrial production, the obtained composite heat-seal film has excellent comprehensive performance, is green and environment-friendly, and has a wide application prospect.

Description

Technical Field

[0001] This application relates to the field of heat-sealing film technology, and more specifically, to composite heat-sealing films and their preparation methods. Background Technology

[0002] Plastic film has become one of the largest-volume and most diverse plastic products in my country, widely used in packaging, electronics, agriculture, building decoration, and daily necessities, accounting for approximately 20% of total plastic product output. With rapid economic and technological development and rising living standards, people are placing increasingly higher demands on the environmental friendliness of plastic packaging films. PET is a high-performance, environmentally friendly material with excellent mechanical and optical properties. It boasts high tensile strength, good rigidity, resistance to stretching and bending, high dimensional stability, gloss, and transparency, and provides good barrier properties against gases (oxygen and carbon dioxide) and water vapor. Therefore, PET is widely used in the packaging industry.

[0003] Ordinary polyester films lack self-heat-sealing properties. To address heat-sealing applications, multilayer co-extrusion processes are commonly used to obtain composite films. These composite films compensate for the heat-sealing shortcomings of single-layer polyester films, achieving excellent heat-sealing performance. However, the poor bonding between the layers in these multilayer co-extruded composite films leads to a decline in their mechanical properties, limiting their wider application. Therefore, there is an urgent need to develop composite heat-sealing films and their preparation methods to ensure that they possess not only excellent heat-sealing performance but also significant mechanical properties, thereby expanding their application range. Summary of the Invention

[0004] To address the issue of poor mechanical properties in existing composite heat-sealing films, this application provides a composite heat-sealing film and its preparation method.

[0005] In the first aspect, this application provides a composite heat-sealing film, which adopts the following technical solution:

[0006] The composite heat-sealing film consists of a base layer and a heat-sealing layer; the base layer comprises the following raw materials in parts by weight: 80-100 parts modified PET, 6-8 parts aminated basalt powder, and 1-3 parts antistatic agent;

[0007] The heat-sealing layer comprises the following raw materials in parts by weight: 60-80 parts PETG, 10-30 parts PCL, 5-9 parts cellulose acetate, 1-3 parts tackifier, and 0.2-1 parts antioxidant.

[0008] By adopting the above technical solution, the matrix layer of this application uses modified PET, aminated basalt powder, and an antistatic agent. Modified PET not only improves the mechanical properties of the matrix layer but also strengthens the connection between the matrix layer and the heat-sealing layer. Aminated basalt powder can be chemically bonded to modified PET, giving the matrix layer excellent mechanical and heat resistance properties. The added antistatic agent facilitates the processing and molding of the raw materials. The heat-sealing layer uses PETG, PCL, and cellulose acetate as the main raw materials, and also adds tackifiers and antioxidants, giving the heat-sealing layer outstanding heat-sealing performance. The composite heat-sealing film of this application consists of a matrix layer and a heat-sealing layer, combining the advantages of each layer material, resulting in a composite heat-sealing film with excellent mechanical and heat-sealing properties, and is environmentally friendly, with broad application prospects.

[0009] Preferably, the modified PET is prepared by the following method:

[0010] First, PET chips are swollen with solvent, then the solvent is evaporated and aged at a constant temperature to obtain aged material. Then, the aged material is mixed with trimethylolpropane and bismuth laurate and put into a reaction vessel, nitrogen gas is introduced, and the reaction is carried out to obtain modified PET.

[0011] Preferably, the mass ratio of the PET chips, solvent, trimethylolpropane, and bismuth laurate is 10:30-50:1-3:0.01-0.1.

[0012] Preferably, the solvent is obtained by mixing tetrahydrofuran and ethyl acetate in a ratio of 2-6:3.

[0013] By adopting the above technical solution, this application uses a solvent to swell PET chips, and the solvent is a mixture of tetrahydrofuran and ethyl acetate. The solvent molecules can enter the spaces between PET molecular chains. After the solvent evaporates, many fine lines will appear on the surface of the PET chips, further increasing the surface area. At the same time, the free volume of the PET molecular chains increases, and the range of chain end movement expands. Subsequently, after mixing with trimethylolpropane and bismuth laurate, the molecular weight of the modified PET can be increased, so that the modified PET achieves a balance between physical properties and processing properties, resulting in superior performance.

[0014] Preferably, the aminated basalt powder is prepared by the following method:

[0015] Basalt powder was soaked in a mixed acid solution and ultrasonically treated before filtration. Then, it was added to a 3-aminopropyltriethoxysilane ethanol solution, heated and stirred for a period of time, filtered, and dried to obtain aminated basalt powder.

[0016] Preferably, the mass ratio of the basalt powder, the mixed acid solution, and the 3-aminopropyltriethoxysilane ethanol solution is 1:2-3:4-5.

[0017] Preferably, the mixed acid solution is obtained by mixing succinic acid, cinnamic acid and water in a mass ratio of 1-4:2-3:20; the mass fraction of the 3-aminopropyltriethoxysilane ethanol solution is 30-50%.

[0018] By adopting the above technical solution, this application uses a mixed acid solution to etch the surface of basalt powder, increasing the surface area of ​​the basalt powder. During the etching process, some succinic acid and cinnamic acid adhere to the surface of the basalt powder, further increasing the roughness of the basalt powder surface. Subsequently, 3-aminopropyltriethoxysilane ethanol solution is added, and after reaction, 3-aminopropyltriethoxysilane is successfully grafted onto the surface of the basalt powder to obtain aminated basalt powder. The aminated basalt powder of this application has good compatibility with modified PET and is tightly bonded by chemical bonds to form a structurally stable matrix layer. At the same time, it can also reduce the viscosity of modified PET, reduce the processing difficulty, and obtain a composite heat-sealing film with better performance.

[0019] Preferably, the antistatic agent is lauryl betaine and / or erucamide.

[0020] By adopting the above technical solution, the antistatic agent of this application is lauryl betaine and / or erucamide, which effectively improves the compatibility of modified PET with other components, keeps the matrix layer homogeneous in all directions, and also makes the composite heat-sealing film have a self-cleaning function.

[0021] Preferably, the tackifier is obtained by mixing rosin resin and acrylic resin in a mass ratio of 4-7:3.

[0022] By adopting the above technical solution, the tackifier of this application is obtained by mixing rosin resin and acrylic resin in a characteristic mass ratio. The two work synergistically to increase the crosslinking density of the heat-sealing layer, making the structure of the heat-sealing layer more compact and the heat-sealing performance of the heat-sealing layer more significant.

[0023] Preferably, the antioxidant is at least one of antioxidant 1010, antioxidant 168, and antioxidant 300.

[0024] Secondly, this application provides a method for preparing a composite heat-sealing film, employing the following technical solution:

[0025] The preparation method of the composite heat-sealing film includes the following steps:

[0026] S1. After thoroughly mixing modified PET, aminated basalt powder, and antistatic agent, add the mixture to an extruder for melting and plasticizing to obtain material A;

[0027] S2. First, plasma treatment is used to treat the mixture of PETG and PCL. Then, cellulose acetate, thickener, and antioxidant are added and mixed evenly. The mixture is then added to an extruder for melt plasticization to obtain material B.

[0028] S3. Material A and material B are subjected to co-extrusion die casting, cooling, tempering, thickness measurement, traction, winding, and slitting processes to obtain a composite heat-sealing film consisting of a base layer and a heat-sealing layer.

[0029] Preferably, in step S1, the extruder temperature is 200-240℃ and the rotation speed is 30-70 rpm; in step S2, the extruder temperature is 220-260℃ and the rotation speed is 20-60 rpm.

[0030] Preferably, the plasma treatment conditions in step S2 are as follows: after evacuation, nitrogen gas is introduced at a flow rate of 40-60 cm³. 3 / s, power of 60KW, voltage of 380V, processing time of 240-300s.

[0031] Preferably, in step S3, the extrusion die forming temperature is 245-250℃; the cooling temperature is 30-50℃; and the tempering temperature is 110-120℃.

[0032] By adopting the above technical solution, this application controls various process parameters during the preparation of the composite heat-sealing film, resulting in a composite heat-sealing film with superior performance. In addition, plasma treatment of PETG and PCL in step S2 generates a large number of active groups on the surface of PETG and PCL, which can be combined with other components in the form of chemical bonds, and also strengthen the connection between the substrate layer and the heat-sealing layer. The preparation method of the composite heat-sealing film of this application is simple, low-cost, and suitable for industrial production. The resulting composite heat-sealing film has broad application prospects.

[0033] In summary, this application has the following beneficial effects:

[0034] 1. The composite heat-sealing film of this application consists of a base layer and a heat-sealing layer. The base layer is made from modified PET, aminated basalt powder, antistatic agent and other raw materials. The raw materials of the heat-sealing layer include PETG, PCL, cellulose acetate, tackifier, antioxidant and other raw materials. The resulting composite heat-sealing film has excellent mechanical properties and heat-sealing performance and has broad market prospects.

[0035] 2. The modified PET of this application is first swollen with a solvent and then undergoes a chain extension reaction with trimethylolpropane, which not only improves the binding ability with other components, but also improves the interlayer connection between the matrix layer and the heat-sealing layer.

[0036] 3. The aminated basalt powder of this application is obtained by etching basalt powder with a mixed acid solution and then grafting 3-aminopropyltriethoxysilane onto its surface; the aminated basalt powder serves as a node to connect other components and form a structurally stable matrix layer. The aminated basalt powder can also improve the heat resistance of the matrix layer.

[0037] 4. The preparation method of the composite heat-sealing film of this application is simple, involves one-time molding, and has low cost, making it suitable for industrial production. The resulting composite heat-sealing film has excellent performance, is environmentally friendly, and expands the application range of composite heat-sealing films. Detailed Implementation

[0038] The present application will be further described in detail below with reference to the embodiments.

[0039] Preparation Examples 1-5 and Comparative Preparation Examples 1 and 2 provide methods for preparing modified PET.

[0040] Preparation Example 1

[0041] Modified PET is prepared by the following method:

[0042] First, 100g of PET chips were swollen with 300g of solvent and allowed to stand for 2 hours. Then, the solvent was evaporated at 90℃ and the chips were kept at the temperature and allowed to stand for 1 hour to obtain aged material. The aged material was then mixed with 10g of trimethylolpropane and 0.1g of bismuth laurate and put into a reaction vessel. Nitrogen gas was introduced and the reaction was carried out at 100℃ for 1 hour to obtain modified PET.

[0043] The solvent is a mixture of tetrahydrofuran and ethyl acetate in a 2:3 ratio.

[0044] Preparation Example 2

[0045] Modified PET is prepared by the following method:

[0046] First, 100g of PET chips were swollen with 350g of solvent and allowed to stand for 2.3h. Then, the solvent was evaporated at 95℃ and the chips were kept at this temperature and allowed to stand for 1.2h to obtain aged material. The aged material was then mixed with 15g of trimethylolpropane and 0.3g of bismuth laurate and put into a reaction vessel. Nitrogen gas was introduced and the reaction was carried out at 105℃ for 0.8h to obtain modified PET.

[0047] The solvent is a 1:1 mixture of tetrahydrofuran and ethyl acetate.

[0048] Preparation Example 3

[0049] Modified PET is prepared by the following method:

[0050] First, 100g of PET chips were swollen with 400g of solvent and allowed to stand for 2.5h. Then, the solvent was evaporated at 110℃ and the chips were kept at this temperature and allowed to stand for 1.5h to obtain aged material. The aged material was then mixed with 20g of trimethylolpropane and 0.5g of bismuth laurate and put into a reaction vessel. Nitrogen gas was introduced and the reaction was carried out at 110℃ for 0.7h to obtain modified PET.

[0051] The solvent is a mixture of tetrahydrofuran and ethyl acetate in a 4:3 ratio.

[0052] Preparation Example 4

[0053] Modified PET is prepared by the following method:

[0054] First, 100g of PET chips were swollen with 450g of solvent and allowed to stand for 2.8h. Then, the solvent was evaporated at 105℃ and the chips were kept at this temperature and allowed to stand for 1.8h to obtain aged material. The aged material was then mixed with 25g of trimethylolpropane and 0.8g of bismuth laurate and put into a reaction vessel. Nitrogen gas was introduced and the reaction was carried out at 115℃ for 0.6h to obtain modified PET.

[0055] The solvent is a mixture of tetrahydrofuran and ethyl acetate in a 5:3 ratio.

[0056] Preparation Example 5

[0057] Modified PET is prepared by the following method:

[0058] First, 100g of PET chips were swollen with 500g of solvent and allowed to stand for 3 hours. Then, the solvent was evaporated at 110℃ and the chips were kept at this temperature and allowed to stand for 2 hours to obtain aged material. The aged material was then mixed with 30g of trimethylolpropane and 1g of bismuth laurate and put into a reaction vessel. Nitrogen gas was introduced and the reaction was carried out at 120℃ for 0.5 hours to obtain modified PET.

[0059] The solvent is a mixture of tetrahydrofuran and ethyl acetate in a 2:1 ratio.

[0060] Comparative Preparation Example 1

[0061] Modified PET is prepared by the following method:

[0062] First, 100g of PET chips are swollen with 300g of solvent and allowed to stand for 2 hours. Then, the solvent is evaporated at 90℃ and the chips are kept warm and allowed to stand for 1 hour to obtain aged material, which is modified PET.

[0063] Comparative Preparation Example 2

[0064] Modified PET is prepared by the following method:

[0065] 100g of PET chips were mixed with 10g of trimethylolpropane and 0.1g of bismuth laurate, and then placed into a reaction vessel. Nitrogen gas was introduced, and the reaction was carried out at 100°C for 1 hour to obtain modified PET.

[0066] Preparation Examples 6-10 and Comparative Preparation Examples 3-5 provide methods for preparing amination-modified basalt powder.

[0067] Preparation Example 6

[0068] Aminated basalt powder is prepared by the following method:

[0069] First, basalt amination basalt powder is prepared by the following method:

[0070] First, grind 100g of basalt powder to 400 mesh; then soak the basalt powder in 200g of mixed acid solution, and sonicate it at 50℃ with a power of 100W for 2h, and filter it; finally, add 400g of 3-aminopropyltriethoxysilane ethanol solution, stir and react at 40℃ with a speed of 400r / min for 2h, filter, and dry to obtain aminated basalt powder;

[0071] The mixed acid solution is obtained by mixing succinic acid, cinnamic acid and water in a mass ratio of 1:2:20; the mass fraction of the 3-aminopropyltriethoxysilane ethanol solution is 30%.

[0072] Preparation Example 7

[0073] Aminated basalt powder is prepared by the following method:

[0074] First, grind 100g of basalt powder thoroughly to 450 mesh; then soak the basalt powder in 220g of mixed acid solution, and sonicate it at 55℃ with a power of 140W for 1.8h, and filter it; finally, add 430g of 3-aminopropyltriethoxysilane ethanol solution, and stir the reaction at 45℃ with a speed of 500r / min for 1.8h, filter it, and dry it to obtain aminated basalt powder;

[0075] The mixed acid solution was obtained by mixing succinic acid, cinnamic acid and water in a mass ratio of 2:2.3:20; the 3-aminopropyltriethoxysilane ethanol solution had a mass fraction of 35%.

[0076] Preparation Example 8

[0077] Aminated basalt powder is prepared by the following method:

[0078] First, grind 100g of basalt powder thoroughly to 500 mesh; then soak the basalt powder in 250g of mixed acid solution, and sonicate it at 60℃ with a power of 160W for 1.5h, and filter it; finally, add 450g of 3-aminopropyltriethoxysilane ethanol solution, and stir the reaction at 50℃ with a speed of 600r / min for 1.5h, filter it, and dry it to obtain aminated basalt powder;

[0079] The mixed acid solution was prepared by mixing succinic acid, cinnamic acid, and water in a mass ratio of 3:2.5:20; the 3-aminopropyltriethoxysilane ethanol solution had a mass fraction of 40%.

[0080] Preparation Example 9

[0081] Aminated basalt powder is prepared by the following method:

[0082] First, grind 100g of basalt powder thoroughly to 500 mesh; then soak the basalt powder in 250g of mixed acid solution, and sonicate it at 70℃ with a power of 210W for 1.2h, and filter it; finally, add 480g of 3-aminopropyltriethoxysilane ethanol solution, and stir the reaction at 55℃ with a speed of 700r / min for 1.2h, filter it, and dry it to obtain aminated basalt powder;

[0083] The mixed acid solution was obtained by mixing succinic acid, cinnamic acid and water in a mass ratio of 3.5:2.8:20; the 3-aminopropyltriethoxysilane ethanol solution had a mass fraction of 45%.

[0084] Preparation Example 10

[0085] Aminated basalt powder is prepared by the following method:

[0086] First, grind 100g of basalt powder thoroughly to 600 mesh; then soak the basalt powder in 300g of mixed acid solution, and sonicate it at 80℃ with a power of 260W for 2 hours, and filter it; finally, add 500g of 3-aminopropyltriethoxysilane ethanol solution, stir and react at 60℃ with a speed of 800r / min for 2 hours, filter, and dry to obtain aminated basalt powder;

[0087] The mixed acid solution is obtained by mixing succinic acid, cinnamic acid and water in a mass ratio of 4:3:20; the 3-aminopropyltriethoxysilane ethanol solution has a mass fraction of 50%.

[0088] Comparative preparation example 3

[0089] Compared with Preparation Example 3, the only difference from Preparation Example 6 is that succinic acid was used instead of cinnamic acid of equal mass.

[0090] Comparative preparation example 4

[0091] Comparing preparation example 4 and preparation example 6, the only difference is that cinnamic acid is used instead of succinic acid of equal mass.

[0092] Comparative preparation example 5

[0093] Comparative preparation example 5 is the same as preparation example 6, except that cinnamic acid and succinic acid are replaced with an equal mass of water.

[0094] Examples 1-7 provide composite heat-sealing films and their preparation methods.

[0095] Example 1

[0096] The composite heat-sealing film consists of a base layer and a heat-sealing layer; the base layer includes the following raw materials: 800g modified PET, 60g aminated basalt powder, and 10g antistatic agent;

[0097] The heat-sealing layer comprises the following raw materials: 600g PETG, 100g PCL, 50g cellulose acetate, 10g tackifier, and 2g antioxidant;

[0098] The modified PET was prepared in Preparation Example 1; the aminated basalt powder was prepared in Preparation Example 6; the antistatic agent was lauryl betaine; the thickener was obtained by mixing rosin resin and acrylic resin in a mass ratio of 4:3; and the antioxidant was antioxidant 1010.

[0099] The preparation method of the composite heat-sealing film includes the following steps:

[0100] S1. After thoroughly mixing modified PET, aminated basalt powder, and antistatic agent, add the mixture to an extruder for melt plasticization. The extruder temperature is 200℃ and the speed is 30rpm to obtain material A.

[0101] S2. First, the mixture of PETG and PCL is treated with plasma. After evacuation, nitrogen gas is introduced at a flow rate of 40 cm³. 3 / s, power of 60KW, voltage of 380V, processing time of 240s, then add cellulose acetate, thickener, antioxidant, mix evenly, add to extruder for melt plasticization, extruder temperature of 220℃, speed of 20rpm, to obtain material B;

[0102] S3. Material A and material B are subjected to co-extrusion die casting, cooling, tempering, thickness measurement, traction, winding, and slitting processes to obtain a composite heat-sealing film consisting of a base layer and a heat-sealing layer; wherein, the co-extrusion die forming temperature is 245℃; the cooling temperature is 30℃; and the tempering temperature is 110℃.

[0103] Example 2

[0104] The composite heat-sealing film consists of a base layer and a heat-sealing layer; the base layer includes the following raw materials: 850g of modified PET, 65g of aminated basalt powder, and 15g of antistatic agent;

[0105] The heat-sealing layer comprises the following raw materials: 650g PETG, 150g PCL, 60g cellulose acetate, 15g tackifier, and 4g antioxidant;

[0106] In this study, the modified PET was prepared by Preparation Example 2; the aminated basalt powder was prepared by Preparation Example 7; the antistatic agent was erucamide; the tackifier was obtained by mixing rosin resin and acrylic resin in a mass ratio of 5:3; and the antioxidant was antioxidant 168.

[0107] The preparation method of the composite heat-sealing film includes the following steps:

[0108] S1. After thoroughly mixing modified PET, aminated basalt powder, and antistatic agent, add the mixture to an extruder for melt plasticization. The extruder temperature is 210℃ and the speed is 40rpm to obtain material A.

[0109] S2. First, the mixture of PETG and PCL is treated with plasma. After evacuation, nitrogen gas is introduced at a flow rate of 45 cm³. 3 / s, power of 60KW, voltage of 380V, processing time of 250s, then add cellulose acetate, thickener, antioxidant, mix evenly, add to extruder for melt plasticization, extruder temperature of 230℃, speed of 30rpm, to obtain material B;

[0110] S3. Material A and material B are subjected to co-extrusion die casting, cooling, tempering, thickness measurement, traction, winding, and slitting processes to obtain a composite heat-sealing film consisting of a base layer and a heat-sealing layer; wherein, the co-extrusion die forming temperature is 246℃; the cooling temperature is 35℃; and the tempering temperature is 112℃.

[0111] Example 3

[0112] The composite heat-sealing film consists of a base layer and a heat-sealing layer; the base layer includes the following raw materials: 900g modified PET, 70g aminated basalt powder, and 20g antistatic agent;

[0113] The heat-sealing layer comprises the following raw materials: 700g PETG, 200g PCL, 70g cellulose acetate, 20g tackifier, and 6g antioxidant; wherein the modified PET is prepared by Preparation Example 3; the aminated basalt powder is prepared by Preparation Example 8; the antistatic agent is obtained by mixing lauryl betaine and erucamide in a mass ratio of 1:1; the tackifier is obtained by mixing rosin resin and acrylic resin in a mass ratio of 2:1; and the antioxidant is antioxidant 300.

[0114] The preparation method of the composite heat-sealing film includes the following steps:

[0115] S1. After thoroughly mixing modified PET, aminated basalt powder, and antistatic agent, add the mixture to an extruder for melt plasticization. The extruder temperature is 220℃ and the speed is 50rpm to obtain material A.

[0116] S2. First, the mixture of PETG and PCL is treated with plasma. After evacuation, nitrogen gas is introduced at a flow rate of 50 cm³. 3 / s, power of 60KW, voltage of 380V, processing time of 270s, then add cellulose acetate, thickener, antioxidant, mix evenly, add to extruder for melt plasticization, extruder temperature of 240℃, speed of 40rpm, to obtain material B;

[0117] S3. Material A and material B are subjected to co-extrusion die casting, cooling, tempering, thickness measurement, traction, winding, and slitting processes to obtain a composite heat-sealing film consisting of a base layer and a heat-sealing layer; wherein, the co-extrusion die forming temperature is 248℃; the cooling temperature is 40℃; and the tempering temperature is 115℃.

[0118] Example 4

[0119] The composite heat-sealing film consists of a base layer and a heat-sealing layer; the base layer includes the following raw materials: 950g of modified PET, 75g of aminated basalt powder, and 25g of antistatic agent;

[0120] The heat-sealing layer comprises the following raw materials: PETG 750g, PCL 250g, cellulose acetate 80g, tackifier 25g, and antioxidant 8g;

[0121] The modified PET was prepared in Preparation Example 4; the aminated basalt powder was prepared in Preparation Example 9; the antistatic agent was prepared by mixing lauryl betaine and erucamide in a mass ratio of 1:2; the tackifier was prepared by mixing rosin resin and acrylic resin in a mass ratio of 6.5:3; and the antioxidant was prepared by mixing antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0122] The preparation method of the composite heat-sealing film includes the following steps:

[0123] S1. After thoroughly mixing modified PET, aminated basalt powder, and antistatic agent, add the mixture to an extruder for melt plasticization. The extruder temperature is 230℃ and the speed is 60rpm to obtain material A.

[0124] S2. First, the mixture of PETG and PCL is treated with plasma. After evacuation, nitrogen gas is introduced at a flow rate of 55 cm³. 3 / s, power of 60KW, voltage of 380V, processing time of 290s, then add cellulose acetate, thickener, antioxidant, mix evenly, add to extruder for melt plasticization, extruder temperature of 250℃, speed of 50rpm, to obtain material B;

[0125] S3. Material A and material B are subjected to co-extrusion die casting, cooling, tempering, thickness measurement, traction, winding, and slitting processes to obtain a composite heat-sealing film consisting of a base layer and a heat-sealing layer; wherein, the co-extrusion die forming temperature is 249℃; the cooling temperature is 45℃; and the tempering temperature is 118℃.

[0126] Example 5

[0127] The composite heat-sealing film consists of a base layer and a heat-sealing layer. The base layer includes the following raw materials: 1000g of modified PET, 80g of aminated basalt powder, and 30g of antistatic agent.

[0128] The heat-sealing layer comprises the following raw materials: 800g PETG, 300g PCL, 90g cellulose acetate, 30g tackifier, and 10g antioxidant;

[0129] The modified PET was prepared in Preparation Example 5; the aminated basalt powder was prepared in Preparation Example 10; the antistatic agent was prepared by mixing lauryl betaine and erucamide in a mass ratio of 2:1; the tackifier was prepared by mixing rosin resin and acrylic resin in a mass ratio of 7:3; and the antioxidant was prepared by mixing antioxidant 1010, antioxidant 168 and antioxidant 300 in a mass ratio of 1:1:1.

[0130] The preparation method of the composite heat-sealing film includes the following steps:

[0131] S1. After thoroughly mixing modified PET, aminated basalt powder, and antistatic agent, add the mixture to an extruder for melt plasticization. The extruder temperature is 240℃ and the speed is 70rpm to obtain material A.

[0132] S2. First, the mixture of PETG and PCL is treated with plasma. After evacuation, nitrogen gas is introduced at a flow rate of 60 cm³. 3 / s, power of 60KW, voltage of 380V, processing time of 300s; then add cellulose acetate, thickener, antioxidant, mix evenly, add to extruder for melt plasticization, extruder temperature of 260℃, speed of 60rpm, to obtain material B;

[0133] S3. Material A and material B are subjected to co-extrusion die casting, cooling, tempering, thickness measurement, traction, winding, and slitting processes to obtain a composite heat-sealing film consisting of a base layer and a heat-sealing layer; wherein, the co-extrusion die forming temperature is 250℃; the cooling temperature is 50℃; and the tempering temperature is 120℃.

[0134] Example 6

[0135] Example 6 is the same as Example 1, except that the antistatic agent is erucamide.

[0136] Example 7

[0137] Example 7 is the same as Example 1, except that the antistatic agent is obtained by mixing lauryl betaine and erucamide in a mass ratio of 1:1.

[0138] To verify the performance of the composite heat-sealing film in Examples 1-7 of this application, the applicant has set up Comparative Examples 1-13, as follows:

[0139] Comparative Example 1

[0140] Comparative Example 1 is the same as Example 1, except that the modified PET was prepared from Comparative Preparation Example 1.

[0141] Comparative Example 2

[0142] Comparative Example 2 is the same as Example 1, except that the modified PET was prepared from Comparative Preparation Example 2.

[0143] Comparative Example 3

[0144] Comparative Example 3 is the same as Example 1, except that the modified PET was replaced with PET chips of equal mass (Preparation Example 1).

[0145] Comparative Example 4

[0146] Comparative Example 4 is the same as Example 1, except that the aminated basalt powder was prepared from Comparative Preparation Example 3.

[0147] Comparative Example 5

[0148] Comparative Example 4 is the same as Example 1, except that the aminated basalt powder was prepared from Comparative Preparation Example 4.

[0149] Comparative Example 6

[0150] Comparative Example 6 is the same as Example 1, except that the aminated basalt powder was prepared from Comparative Preparation Example 5.

[0151] Comparative Example 7

[0152] Comparative Example 7 is the same as Example 1, except that an equal mass of basalt powder (400 mesh) was used to replace the aminated basalt powder (Preparation Example 6).

[0153] Comparative Example 8

[0154] Comparative Example 8 is the same as Example 1, except that: no aminated basalt powder is added (Preparation Example 6).

[0155] Comparative Example 9

[0156] Comparative Example 9 is the same as Example 1, except that the antistatic agent used is trihydroxyethylmethyl quaternary ammonium methyl sulfate.

[0157] Comparative Example 10

[0158] Comparative Example 10 is the same as Example 1, except that the antistatic agent used is octadecyl dimethyl hydroxyethyl quaternary ammonium nitrate.

[0159] Comparative Example 11

[0160] Comparative Example 11 is the same as Example 1, except that the tackifier is only rosin resin.

[0161] Comparative Example 12

[0162] Comparative Example 12 is the same as Example 1, except that the tackifier is only acrylic resin.

[0163] Comparative Example 13

[0164] Comparative Example 13 is the same as Example 1, except that in step S2, the mixture of PETG and PCL is not treated with plasma, but is directly mixed with cellulose acetate, thickener and antioxidant.

[0165] The main properties of the composite heat-sealing films in Examples 1-7 and Comparative Examples 1-13 of this application were tested respectively, and the following results were obtained, as shown in Table 1:

[0166] The tensile breaking properties of the composite heat-sealable film were tested in accordance with GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets"; the heat-sealing properties of the composite heat-sealable film were tested in accordance with QB / T 2358-1998 "Test method for heat-sealing strength of plastic film packaging bags".

[0167] Table 1:

[0168]

[0169] As shown in Table 1 above, the composite heat-sealing films in Examples 1-7 have a much better overall performance than those in Comparative Examples 1-13, indicating that the composite heat-sealing film of this application has high tensile strength and elongation at break, high heat-sealing strength, low heat-sealing temperature, and broad application prospects.

[0170] As can be seen from Example 1 and Comparative Examples 1 and 2, the modified PET in Example 1 was prepared by Preparation Example 1. In Preparation Example 1, the PET was first swollen in a solvent and then underwent a chain extension reaction with trimethylolpropane. Compared with Comparative Examples 1 and 2, the composite heat-sealing film obtained in Example 1 has better mechanical properties, indicating that the PET can react better with trimethylolpropane after being swollen in a solvent. The modified PET obtained not only has excellent mechanical properties, but also improves its binding ability with other components.

[0171] As can be seen from Example 1 and Comparative Example 3, the modified PET in Example 1 was prepared by Preparation Example 1. Compared with the unmodified PET used in Comparative Example 3, the composite heat-sealing film obtained in Example 1 has better heat-sealing performance, indicating that the modified PET helps the substrate layer and the heat-sealing layer to bond more tightly.

[0172] As can be seen from Example 1 and Comparative Examples 4 and 5, the aminated basalt powder in Example 1 was prepared by Preparation Example 6. In Preparation Example 6, the basalt powder was treated with a mixed acid solution of succinic acid and cinnamic acid. Compared with Comparative Examples 4 and 5, the composite heat-sealing film obtained in Example 1 has better mechanical properties, indicating that succinic acid and cinnamic acid have a synergistic effect and can effectively etch basalt powder. At the same time, they can also make the surface of basalt powder acquire active groups. In addition, the cinnamic acid molecule contains a benzene ring, which can improve the compatibility between aminated basalt powder and modified PET.

[0173] As can be seen from Example 1 and Comparative Example 6, the aminated basalt powder of Example 1 was prepared by Preparation Example 6. In Preparation Example 6, the basalt powder was first treated with a mixed acid solution and then reacted with a 3-aminopropyltriethoxysilane ethanol solution. Compared with Comparative Example 6, the composite heat-sealing film obtained in Example 1 has outstanding tensile fracture properties, indicating that after the basalt powder is treated with a mixed acid solution, it is more conducive to the grafting of 3-aminopropyltriethoxysilane onto the surface of the basalt powder.

[0174] As can be seen from Example 1 and Comparative Example 7, the aminated basalt powder in Example 1 was prepared by Preparation Example 6. Compared with the unaminated basalt powder in Comparative Example 7, the composite heat-sealing film obtained in Example 1 has better mechanical properties, indicating that using aminated basalt powder as a node to connect other components makes the structure of the matrix layer more compact.

[0175] As can be seen from Example 1 and Comparative Example 8: Example 1 added amino-modified basalt powder (Preparation Example 6), compared with Comparative Example 8 which did not add amino-modified basalt powder. The composite heat-sealing film obtained in Example 1 not only has excellent mechanical properties, but also outstanding heat-sealing performance. This shows that amino-modified basalt powder can not only enhance the mechanical properties of the composite heat-sealing film, but also improve the heat resistance of the substrate layer, so that the composite heat-sealing film maintains significant heat-sealing strength, and the appearance of the substrate layer is intact, resulting in a good heat-sealing effect.

[0176] As can be seen from Examples 1, 6, 7 and Comparative Examples 9, 10, the antistatic agents in Examples 1, 6, and 7 are lauryl betaine and / or erucamide. Compared with Comparative Examples 9 and 10, the composite heat-sealable films obtained in Examples 1, 6, and 7 have significantly better tensile properties. This indicates that the use of lauryl betaine and / or erucamide as antistatic agents facilitates the processing of raw materials and yields composite heat-sealable films with superior performance.

[0177] As can be seen from Example 1 and Comparative Examples 11 and 12, the tackifier in Example 1 is a mixture of rosin resin and acrylic resin. Compared with Comparative Examples 11 and 12, the heat-sealing performance of the composite heat-sealing film obtained in Example 1 is significantly improved, indicating that rosin resin and acrylic resin have a synergistic effect, which greatly improves the heat-sealing performance of the heat-sealing layer.

[0178] As can be seen from Example 1 and Comparative Example 13, in step S2 of Example 1, plasma treatment was used to treat the mixture of PETG and PCL. Compared with Comparative Example 13, the overall performance of the composite heat-sealing film obtained in Example 1 is better than that in Comparative Example 13, indicating that plasma treatment of the mixture of PETG and PCL helps to enhance the bond between the substrate layer and the heat-sealing layer.

[0179] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A composite heat-sealable film, characterized in that, It consists of a base layer and a heat-sealing layer; the base layer comprises the following raw materials in parts by weight: 80-100 parts modified PET, 6-8 parts aminated basalt powder, and 1-3 parts antistatic agent; The heat-sealing layer comprises the following raw materials in parts by weight: 60-80 parts PETG, 10-30 parts PCL, 5-9 parts cellulose acetate, 1-3 parts tackifier, and 0.2-1 parts antioxidant; The modified PET is prepared by the following method: First, PET chips are swollen with solvent, then the solvent is evaporated and aged at a constant temperature to obtain aged material; after the aged material is mixed with trimethylolpropane and bismuth laurate, it is put into a reaction vessel, nitrogen gas is introduced, and the reaction is carried out to obtain modified PET; The aminated basalt powder is prepared by the following method: Basalt powder was soaked in a mixed acid solution and ultrasonically treated before filtration. Then, 3-aminopropyltriethoxysilane ethanol solution was added, and the mixture was heated and stirred for a period of time. After filtration and drying, amino-modified basalt powder was obtained. The mixed acid solution was prepared by mixing succinic acid, cinnamic acid and water in a mass ratio of 1-4:2-3:

20.

2. The composite heat-sealable film according to claim 1, characterized in that, The mass ratio of the PET chips, solvent, trimethylolpropane, and bismuth laurate is 10:30-50:1-3:0.01-0.

1.

3. The composite heat-sealable film according to claim 1, characterized in that, The mass ratio of the basalt powder, mixed acid solution, and 3-aminopropyltriethoxysilane ethanol solution is 1:2-3:4-5.

4. The composite heat-sealable film according to claim 1, characterized in that, The mass fraction of the 3-aminopropyltriethoxysilane ethanol solution is 30-50%.

5. The composite heat-sealable film according to claim 1, characterized in that, The antistatic agent is lauryl betaine and / or erucamide.

6. The composite heat-sealable film according to claim 1, characterized in that, The tackifier is obtained by mixing rosin resin and acrylic resin in a mass ratio of 4-7:

3.

7. A method for preparing the composite heat-sealing film according to any one of claims 1-6, characterized in that, Includes the following steps: S1. After thoroughly mixing modified PET, aminated basalt powder, and antistatic agent, add the mixture to an extruder for melting and plasticizing to obtain material A; S2. First, plasma treatment is used to treat the mixture of PETG and PCL. Then, cellulose acetate, thickener, and antioxidant are added and mixed evenly. The mixture is then added to an extruder for melt plasticization to obtain material B. S3. Material A and material B are subjected to co-extrusion die casting, cooling, tempering, thickness measurement, traction, winding, and slitting processes to obtain a composite heat-sealing film consisting of a base layer and a heat-sealing layer.

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